Yes, given the 4K WEB-DL releases it seems a few groups/individuals possess the knowledge of decrypting L1 content. Occasionally an L1 key will be leaked but is burnt quickly. I think the requirement of "unique" keys stops an interest in a public effort to make L1 content work under Linux, especially as there is already support for L3 content. Even under Windows and macOS end users must be using Microsoft Edge or Safari (platform specific) - given Chrome's huge marketshare I imagine lots of non Linux users are consuming exclusively L3 content on desktop platforms so I'm not sure there's much demand for full/ultra HD content, although many users may simply be unaware that their browser choice affects the quality of content they are streaming.

Nah, it's HDCP that's cracked. You can grab HDCP strippers (or rather, "splitters"/"signal multiplexers" that happen to strip HDCP) for cheap on alibaba and the likes. From there, all you need is a HDMI framegrabber or if you want the best possible quality, an SDI converter and a BlackMagic Decklink SDI capture card. That's a few hundred bucks.

Well, then you couldn't have a play button, or pause button, or video text over the top of the video; unless there was some way of turning the GPU into a hardware-level compositor... which is generally not recognized as a good idea.